A circuit with extremely low input bias current, such as an amplifier or a buffer circuit, may use insulated gate field effect transistors, for example, Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) as an input device. MOSFETs have a gate electrode which is electrically insulated from the main semiconductor n-channel or p-channel by a very thin layer of insulating material named gate oxide. The gate oxide can be a silicon dioxide. In manufacturing processes using MOSFETs, for example complementary MOS (CMOS) manufacturing processes, continually thinner gate oxides of MOSFETs have been a critical feature of the overall scaling-down of transistor dimensions to achieve higher density of circuitry and lower power dissipation. However, a reduction in the gate oxide thickness causes undesirable leakage current at the gate through the thin oxide gate dielectric due to tunneling. To reduce the current leakage at the gate, some conventional art has used a thicker gate dielectric which requires a much larger transistor in order to design for low noise, thus limiting the density of the circuitry. Accordingly, the gate current leakage can be a limiting factor in further device down-scaling.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present disclosure as set forth in the remainder of the present disclosure.